PWR core power distribution verification experimental analysis based on precisely calculated SPND response current

BackgroundThe power distribution verification experiment is critical to confirm consistency between a reactor core's actual operating power distribution (measured value) and reactor physics design software calculations, as it evaluates both software reliability and alignment between the core's actual operation and design predictions. However, accurate core power distribution measurements rely on in-core detector response signals, and traditional Pressurized Water Reactor (PWR) core physics software lacks sufficient accuracy in calculating Self-Powered Neutron Detector (SPND) response current—this undermines the reliability of power distribution verification.PurposeThis study aims to address the inaccuracy of traditional software in SPND response current calculation and its impact on power distribution verification with emphasis on the comparison with that accurately calculated by using NECP-Bamboo (a PWR core physics software independently developed by the NECP team of Xi'an Jiaotong University), and quantitatively analyze how this precise calculation improves power distribution verification results.MethodsFirstly, the actual measurement data from an AP1000 reactor core were collected, including SPND response current and corresponding actual core power distribution data. Then, the NECP-Bamboo was used to calculate the AP1000 core's SPND response current under the same operating conditions, and these values were compared with the measured data to assess the software's accuracy. Subsequently, the core power distribution was derived using NECP-Bamboo's calculated SPND response current following standard procedures. Finally, statistical indicators, i.e., root mean square error, relative error, were used to quantitatively compare errors between the two software.ResultsBased on the AP1000 core's actual measurement data, the verification results show clear advantages of NECP-Bamboo: its accuracy in calculating SPND response current is significantly higher than that of the original dedicated software; using its precisely calculated SPND response current effectively reduces core power distribution verification errors; and its power distribution error is consistently smaller than that of the original software.ConclusionsResults of this study confirm that NECP-Bamboo outperforms the in-service AP1000 original dedicated software in SPND response current calculation for PWR cores; its precise SPND response current calculation directly reduces reactor power distribution verification errors, enhancing the reliability of results. It indicates that NECP-Bamboo can serve as a reliable tool for PWR core physics analysis and power distribution verification in engineering practice.